DARWIN'S THEORY UNSHAKEN 33 



same natural forces which are now at work. And, more- 

 over, the examination of the successive stratified deposits 

 of the earth's crust has yielded the remains of whole 

 series of animals and of plants (simpler in character the 

 older and deeper the rock in which they occur), which 

 can be satisfactorily explained and interpreted as the 

 ancestral forms from which present organisms have been 

 developed. 



The theory of the natural selection of variations as the 

 moving spring in the gradual development of living forms 

 from simplest living matter is Darwin's theory. It is not 

 possible to find any naturalist of consideration who does 

 not accept it. There are various views held and discussed 

 as to the cause of variation, as to the importance of small 

 and of big variations, as to the non-transmissibility of 

 some kinds of variation, and as to various peculiarities in 

 regard to inheritance. They do not for the most part 

 touch the main features of Mr. Darwin's theory. No 

 doubt we are learning and shall learn more about the facts 

 of variation and the details of the process of hereditary 

 transmission, but such increase of knowledge has not 

 tended to undermine Mr. Darwin's theory, and does not 

 seem at all likely to do so. 



On the occasion of the celebration at Cambridge in 

 1909 of the centenary of Darwin's birth, I was invited by 

 the Vice-Chancellor, on behalf of the University, to deliver 

 in the Senate-house an address, others being given by 

 representatives of the United States (Prof. Osborne), of 

 Germany (Prof. Hertwig), and of Russia (Prof. Metchni- 

 koff). The following is the text of that address : 



" I feel it a great honour to be called upon to speak 

 here to-day, and to stand, on behalf of the naturalists 

 of the British Empire, by the side of the distinguished 

 men whose orations you have just heard. 



" I think that the one thing about Charles Darwin 

 3 



